<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .div {
            /* div默认是block */
            display: inline;
        }
        .span {
            /* span默认是inline */
            display: block;
        }
        .none {
            /* 隐藏 */
            display: none;
        }
    </style>
</head>
<body>
    <h2>默认的div</h2>
    <div class="div">1</div>
    <div class="div">2</div>
    <div class="div">3</div>
    <h2>默认的span</h2>
    <span class="span">1</span>
    <span class="span">2</span>
    <span class="span">3</span>
    <h2>display: none</h2>
    <div class="none">1</div>
</body>
</html>